In accordance with CCITT (Comite Consultatif International de Telegraphie et Telephonie), the typical method employed for selection of a modulation mode for transmission of data (typically the contents of a file) is the automode method described in U.S. Pat. No. 4,931,250, Greszczuk, which is hereby incorporated by reference. The automode method provides for selection of a common modulation mode negotiated between a call and an answer modem for transmission of data. This is done by automatically choosing the modulation mode to achieve the highest common data rate. But, if the total connection time is to be minimized, the modulation mode selected by this method is sometimes inefficient because the automode method does not consider the size of the data file that has to be transferred or the time that is required for training the modems embodying the selected modulation mode before the actual transmission of data can commence. It is known that in order to communicate using the modulation modes which typically support higher data rates, a significant amount of time is required for training the modem's receivers and echo cancellers to sustain the higher data rates. However, in cases where the file to be transferred is short (i.e., has low data content), the training time may be longer than the actual time it takes to transfer the file. It is also understood that from the time the call is made to the time the entire contents of the file have been transferred, the communication channel and the modems are busy and hence unavailable to other users.
Thus, there is a need for an automatic modulation mode selecting unit and method for modems that provide efficient selection of a modulation mode and a related data rate before commencing data transmission.